The present invention relates to a new and distinct cultivar of Buddleja, botanically known as Buddleja davidii, and hereinafter referred to by the name ‘Summer Skies’.
The new Buddleja was discovered and selected by the inventors as part of a larger mutant screen for phenotypically unique individuals at Storrs, Conn. in June, 2007. The mutant population was derived from chemical mutagenesis of the commonly available seed Buddleja davidii Assorted Colors (is a descriptor for a commonly sold type of seed that is comprised of seed from various cultivars), which is not patented. Ethylmethane sulfonate (EMS) was the chemical mutagen used according to standard protocols for seed mutagenesis. Seeds were imbibed overnight then treated for four hours in buffered EMS (200 millimolar). The mutagenized seeds were germinated and grown on under greenhouse conditions. ‘Summer Skies’ presented itself early on as a unique variegated mutant from over two thousand seedlings.
Asexual reproduction of ‘Summer Skies’ by cuttings has shown that the periclinal leaf variegation is stable and reproduced true-to-type in successive generations. The original plant was propagated asexually in late spring 2008 by softwood to semi-hardwood stem cuttings taken from greenhouse-grown materials at Storrs, Conn. Fifty cuttings were potted and evaluated out of doors under drip irrigation for one growth season. An additional five rooted stem cuttings were also grown under field conditions at Storrs, Conn. and evaluated over a three year period (2008 through 2010). Following their first growing season, the original fifty plants propagated were distributed in early summer of 2009 to test locations and evaluated for ease of asexual propagation, stability of the variegation and landscape performance. These test locations included controlled environments in Lebanon and Hamden, Conn., Grand Haven, Mich. and Pensacola, Fla. It was found that ‘Summer Skies’ was easily propagated by stem cuttings. During all asexual propagation, the characteristics of the original plant have been maintained. Plants derived from stem cuttings exhibit characteristics identical to those of the original plant.
Cuttings may be taken from June through August from field-grown materials, however greenhouse-grown materials root readily throughout the year. Nearly 100% of cuttings root and produce profuse root systems under intermittent mist in 7 to 10 days with the application of rooting hormone (1000 parts per million indole-3-butyric acid). Cuttings rooted by early summer may be grown to 2 gallon container size in one growing season. Vigorous, highly floriferous plants can be marketed by the second growing season following over-wintering dormancy and pruning.